Thermal decomposition of sol–gel synthesized bismuth citrate

Abstract This paper investigates the thermal decomposition of bismuth citrate sol–gel precursors using thermogravimetry, derivative thermogravimetry and differential thermal analysis, as well as Fourier transform infrared spectroscopy and powder X-ray diffraction with Rietveld refinement analysis. Citric acid effectively complexes Bi 3+ to form bismuth citrate monohydrate after drying at 100 °C. Upon further heating, dehydration and decomposition of excess citric acid occurs, followed by the decomposition of bismuth citrate to form a mixture of α-Bi 2 O 3 and bismuth oxide acetate at ~ 300 °C. An intermediate bismuth subcarbonate phase was detected upon further heating before final decomposition to Bi 2 O 3 . The subcarbonate phase has not been reported in bismuth citrate decomposition studies before. A partial phase transition from α-Bi 2 O 3 to γ-Bi 2 O 3 was also observed after heating to 700 °C and 750 °C.